In a communication network, an access network is configured to transmit service data of a User Equipment (abbreviated as UE) and an application network is configured to control the processing of the service data, that is, to provide services to the UE.
In the prior art, steps for allocating resources to the access network include: A UE obtains an IP address by creating a default bearer and sets up a Public Data Network (abbreviated as PDN) connection; the UE negotiates a resource required by a service, such as Quality of Service (abbreviated as QoS), codec, etc. with the application network; the application network forms a service request and sends the service request to a Policy Charging and Rules Function (abbreviated as PCRF) entity, and the PCRF entity creates Policy Charging Control (abbreviated as PCC) rules according to the service request, the PCRF entity delivers the PCC rules to a Packet Data Network Gateway (abbreviated as P-GW); the P-GW, according to the PCC rules, sets up a dedicated service bearer required by the service; and the UE exchanges service data with a remote end (such as another UE) through the set up dedicated service bearer.
The method for setting up a service bearer in the prior art has the following problem. Through the above steps, the bearer for the UE to exchange service data is set up, during the process that the UE exchanges service data, if a resource of the access network is changed, for example, the access network is congested, the previously set up service bearer does not match the changed access network resource and the previously formed service request does not match the changed access network resource either; as a result, the QoS of the service deteriorates and the service is even caused to be interrupted.